Gnawing damage by rodents to the seedlings of Fagus crenata and Quercus mongolica var grosseserrata in a temperate Sasa grassland deciduous forest series in southwestern Japan

The effects of dwarf bamboo, Sasa, cover On the initial mortality of hardwood seedlings were investigated by transplanting 1-year-old beech (Fagus crenata) and current-year oak (Quercus mongolica var. grosseserrata) seedlings to three different stands; old-growth beech and secondary oak forests with Sasa undergrowth, and a Sasa grassland in a grassland-forest series near the top of Mt Jippo, southwestern Japan. The most frequent cause of seedling mortality was gnawing of the stems by rodents. Tn the beech forest, the gnawing was more likely to occur under Sasa cover, suggesting that it provides a good habitat for rodents on the beech forest floor. The Sasa undergrowth may thus play an important role in regeneration of beech forest. In the oak forest, mortality of both species was low and only a little gnawing occurred during a year. However, no natural oak seedlings were found in the forest even after a mast year. This may be because most of the acorns disappeared before establishment. The early-stage demography of hardwood seedlings such as oak may thus play an important role in regeneration of oak forest. In the Sasa grassland where the seed supply is small, almost all of the seedlings died from gnawing regardless of the presence of Sasa cover. These factors prevent the recruitment of a sizable seedling bank. Rodents may thus play an important role in maintenance of the Sasa grassland.